1. Field of the Invention
This invention relates to an electrostatic copying apparatus, particularly one called a shell type.
2. Description of the Prior Art
It is known to those skilled in the art that electrostatic copying apparatuses of the shell type comprising an upper supporting frame and a lower supporting frame connected to each other for free relative pivoting movement between an open position and a closed position (usually the lower supporting frame is disposed at a predetermined position and the upper supporting frame is mounted on the lower supporting frame so as to pivot freely between the open position and the closed position) have been proposed and come into commercial acceptance. Such a shell-type electrostatic copying apparatus has the general advantage that when the upper supporting frame is caused to pivot to the open position, most of a copying paper conveying passage in which a copied image is formed is open, and therefore, in the event of paper jamming in the paper conveying passage, the paper can be easily removed out of the passage.
In this type of conventional electrostatic copying apparatus, importance is attached to the removing of paper that has jammed up particularly in a transfer zone and a fixing device. For this reason, a rotating drum, a developing device, etc. are mounted on the upper supporting frame and the lower supporting frame and the upper supporting frame are connected so that they can pivot freely about a fulcrum in the paper supply side of the apparatus. Consequently, in ralation to these arrangements, the apparatus has various inconveniences. Specifically, the paper conveying passage cannot be fully opened at its upstream side portion and in the event of paper jamming at this part, the paper cannot be easily taken out. Especially where a plurality of paper cassettes are disposed vertically on the upstream side of the paper conveying passage, the removal of paper that has jammed up is difficult. Because the developing device moves as a unit with the upper supporting frame, toner particles are supplied by inserting a toner cartridge from the front side of the copying apparatus and mounting it detachably. Because of this, the feeding of the toner particles is likely to become non-uniform in the front-back direction of the developing device, and also it is impossible to determine clearly the amount of the toner particles that remain. In addition, since the rotating drum also moves as a unit with the upper supporting frame, the cleaned surface of a photosensitive material disposed on the peripheral surface of the rotating drum cannot be easily observed visually, and it is difficult to confirm the cleaning action of the apparatus.